Dude, I have the same EXACT E6600 Mobo, 8 GB Ram, and the GeForce 550 TI 1 GB, same Windows as you, and mine runs GREAT! I just got the GeForce and I LOVE it! Don't get me wrong, things could be more high-end here, but, this all runs just fine. You won't be disappointed with that graphics card!
Good luck!
Scott